1. Division of Cardiovascular Surgery, Hospital of the University of Pennsylvania, Philadelphia (C.R.B., S.H.-S., C.B., P.A., M.A.A.).
2. Washington University, School of Medicine, St Louis, MO (D.M.Z.).
3. Vanderbilt University School of Medicine, Nashville, TN (J.K.).
4. Stony Brook School of Medicine, NY (D.J.R.).